Reconstructing functional performance and resilience in submerged coastal heritage: the offshore harbour system of Aegina

Submerged harbour structures often preserve only late-stage morphology, obscuring their original function. The Rubble-mound Conical Structures (RmCS) of Aegina (Greece) form a large offshore system with no clear parallels in ancient world. Despite extensive documentation, their function remains unresolved. This study reassesses the RmCS using functional-lifespan analysis as a non-intrusive interpretative tool. Focusing on c. 480–458 BCE, we reconstruct initial geometry relative to sea level, model crest evolution under local wave forcing and alternative palaeo–sea-level scenarios, and evaluate performance using wave transmission and navigability indicators. Results are extended to the Roman period and compared with Pausanias’ description for landscape reconstruction. The RmCS were most likely ineffective as wave-attenuation structures and instead functioned as a resilient offshore long-term functional barrier restricting access. By linking structural evolution, functional performance, and historical perception, this study demonstrates how functional-lifespan modelling can transform contemporaneous degraded submerged structural remains into interpretable maritime heritage infrastructure.